I don't think MS future is very bright. Probably in 4-5 years it will split and the parts will be just another company in their respective fields.
I really think that's a bit over the top in terms of Microsoft going the way of the ghost.
But, I agree with part of your statement: Phones were never known to have complex programs, people use these apps because using the web-interface on a phone is not very conducive.
On a PC they have been using programs/apps for ages, but the majority of users have moved away from using almost any programs on their computer in favor of using the web/browser.
Others have said above that no-one will use the Store, they will just go to the web if they want to download a program. Part of that has to be due to that fact that most users have been conditioned to work that way for years and years. There has NEVER been a "Windows (App) Store" until now.
(I don't even consider Windows 8 because laptop/desktop users either weren't aware of it or never wanted to use it because the message they got was it was for 'tablets/touch' only).
So if you think about it users who started using Windows with XP or 7 have never known an app store for their PC. Microsoft has to educate these users about the benefits of an app over a website. THERE ARE BENEFITS - it's not made up.
I've listed a few use cases of my own but obviously they're anecdotal - but I have found my own habits changing. Where in the past I'd go to the web to find something, I now first look in the Store. (Example, recently I wanted to make a photo collage for my daughter's birthday. I used the Store to find an app that let me do it Phototasic Collage - I found it and installed it faster using the Store than digging through Google search results attempting to avoid scam software).
I believe there is a case for Windows Apps, Microsoft just needs to continue to educate users of the Stores existence and continue making the benefits clear to users. In time, I feel a lot more people will end up in the Store as well.